Question

Describe, using named examples, the major feeding groups of stream macroinvertebrates, their role in food webs and how they may change along the river continuum. Give two reasons why this type of information is useful when undertaking assessment of water quality.

Answer 1

The major feeding groups of stream macroinvertebrates are-

• Shredders- they consume leaf or litters of plants. Eg - Stone fly

• Scrapers- they consume algae and related materials Eg- Drunella

• Piercers/filters- they collect FPOM from water column. Eg- mayfly

• Collectors- they are gatheres who collect fine particulate organic matter from bottoms.

Eg- Beetle and dipteran

• Predators- they feed on other consumers and preys .eg- water beetle , Dragonfly.

There role in food webs is very important because they are on all the levels of tropic in the ecosystem. They are decomposers, Predators as well as consumers in the food web. They link important food chains between different other invertebrates and vertebrates. They change along the river continuum depending upon the flow, presence of decaying organic matter , presence of quantity of coarse particulate matter and fine particulate matter.

The two reasons why this type of information is useful when undertaking assessment of water quality because they serve as a purpose of decomposers in food web, they maintain a proper clean water steam flow and hence maintaining the overall water quality. So one of the reason is that their presence reflects the water quality. Other reason is BOD( biochemical oxygen demand) . For accessing the amount of oxygen water will require further for purification can be assessed by this. As the more organic content they decompose, the higher will be the oxygen demand and hence more polluted the water is.

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